1. Field
Example embodiments relate to a chemical sensor including a sensing member having a relatively large area and a nano structure, for example, a nanowire, for use in an upper electrode.
2. Description of the Related Art
Studies have been conducted on the diagnosis of disease by measuring the components of a chemical compound in the breath of people. For example, in the case of lung cancer patients and breast cancer patients, approximately 10 kinds of volatile organic compounds are discharged in the breath, unlike in a healthy person. Thus, a chemical sensor analyzing the components of the volatile organic compounds may be used for detecting diseases. A conventional chemical sensor may measure an amount of a chemical compound using a characteristic of a compound molecule in which the electrical conductivity or specific electrical resistance of the compound molecule changes according to the adsorption of the chemical compound.
Volatile organic compounds (VOCs) may be relatively stable, and thus, analyzing their components using an electrical method may be difficult. Gas chromatography (GC) may be used to analyze the VOCs; however, the sensor may be relatively large and expensive.
Sensors using semiconductors offer some advantages. For example, sensors using semiconductors may be relatively inexpensive and the detection may be performed in real-time. Additionally, sensors using semiconductors may be relatively small. However, detection sensitivity associated with the sensors using semiconductors may be relatively low and detecting stable materials, e.g. the VOCs, may be difficult.
A VOC measuring sensor using a conductive polymer has been proposed. When the conductive polymer adsorbs a VOC, the work function of the conductive polymer changes due to various reasons, for example, the swelling of the conductive polymer, and thus, a VOC may be detected by measuring the changes of the work function of the conductive polymer. However, sensors using a conductive polymer still have difficulty in reaching a detection capability of a few ppm. The difficulty is due to the volume of a sensing channel being too large to detect a small amount of electrical change according to adsorbed material.